Interactive rigid body manipulation with obstacle contacts

The interactive manipulation of rigid objects in virtual reality environments requires an object behaviour which is at least physically plausible to be useful for applications like interactive assembly simulation or virtual training. Physically plausible behaviour implies that collisions between simulated solid objects are taken into account, and that the motion of objects with obstacle contacts can be controlled without force feedback mechanisms in an intuitively correct manner. We present a real-time framework which enables the simulation of interactively controlled solid objects with a dynamically changing set of contact constraints. In this paper, all contact configurations are replaced by a canonical set of point contacts, which is updated dynamically. The basic step to determine the contact forces and the object motion consists in the solution of a non-linear complementarity problem (NCP), which results from the unilateral contact conditions together with an adequate discretization of the corresponding differential equations of motion.